SPLITTING COLORS
The Splitting Color illusion is all about how we perceive colors. We start off with two identical, flickering colored stripes that remain unchanged throughout the demonstration. However, different surroundings will make these stripes appear completely different. When the stripe is flanked by a yellow/blue pattern, drifting to the left, it changes appearance, and looks red and cyan, drifting to the right, while the same stripe, flanked by a red/cyan pattern drifting to the right, suddenly looks yellow and blue, drifting to the left. This illusion shows that one and the same object can look completely different depending on its surroundings. In the Splitting Colors illusion you see a flickering, colored stripe that is constructed by mixing two different color patterns that drift in opposite directions: a red/cyan pattern drifting to the right and a blue/yellow pattern drifting to the left. After the mixing, no clear motion direction can be identified. Next, the flickering stripes are each flanked by one of the drifting color patterns from which it was constructed. This dramatically changes the perception of the stripe. When the (upper) stripe is flanked by pattern 1 (a yellow/blue pattern), then our brain somehow ignores these colors in the stripe. Therefore, what is left is pattern 2 (red/cyan). The same logic can be applied to the lower stripe, but in the opposite direction. It is flanked by pattern 2 (red/cyan). As a result, our brain ignores these colors in the stripe and what is left (so what you see) is pattern 1 (yellow/blue). Why does our brain start to ignore those colors of the flanker? What happens is that our brain segments the stripe into two separate layers. Layer 1, consisting of the colors of the flanking pattern, is seen as the background pattern. The remaining colors are segmented into a different layer, layer 2, which is moving in the opposite direction and is seen as the foreground pattern and is therefore perceived. Because both mixed stripes are surrounded by different patterns, different colors are perceived as the foreground for each stripe. With this illusion we show how flexible our visual perception is and how our brain interprets visual information, depending on its surrounding context.
*** This illusion won the 1st prize in the 2015 Best Illusion of The Year Awards***
FILLING IN THE AFTERIMAGE
Fixate your gaze on the central black dot for some time while the figures cycle. After several iterations you’ll start noticing that the empty outlines fill in with ghostly redish or bluish colors. These illusory colors are called “afterimages”. Interestingly, the colors of the afterimages vary, which is puzzling because they come from the same original figure. Moreover, the shape of the outlines determines the filled-in color, which is complementary to the color of the same shape in the original figure. It is well known that viewing a colored surface can induce a vivid afterimage of the complementary color (for example, the color red induces a greenish/bluish afterimage). Our illusion shows that a colored image can produce different colored afterimages at the same retinal location. The perceived afterimage colors depend on the contours that are presented after the colored image. More specifically, the illusion shows that the afterimage colors spread and mix between those contours. In addition, alternating different contours after the original colored image causes rapidly switching afterimage colors.
*** This illusion won the 1st prize in the2008 Best Illusion of The Year Awards***
FLEXIBLE COLORS
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One colored image can lead to different color impressions, depending on the colourless luminance profile that is presented on top of the colored image. In both demonstrations, the underlying colours do not change throughout the presentation; the only variation is the positioning of the grey lines on top of the colored image. The visual system averages the colors presented within an outlined area. As the different positioning of the oulines changes the shape of the outlined areas, also the result of the color averaging will be different. the As a result the color impression is very different for the different images. This illusion is a demonstration of how in our brain color and contour information is combined before the eventual perception is determined.
*** This illusion won the 2nd prize in the2014 Best Illusion of The Year Awards***
Published as:Vergeer, M., Anstis, S., and van Lier, R. (2015). Flexible color perception depending on the shape and positioning of achromatic contours. Frontiers in Psychology. 6, 620.
CAUGHT INSIDE A BUBBLE
In this illusion you can see colors that are not presented on the screen. An image of colored bull’s eyes is alternated with an image containing different sized greyscale bubbles. Although these bubbles are colorless, they will actually appear to be colored. These illusory colors are the afterimages of the bull’s eye colors. The intriguing thing is that the colors of the bubbles appear to be completely different, depending on the size of the bubble. Each bubble ‘captures’ the afterimage of the bull’s eye color that matches the size of the bubble. One colored image causes multiple, completely different afterimages. When your brain is confronted with the same color at the same location for a prolonged period of time, it will become less sensitive to this color. As a consequence, if you subsequently stare at a colorless image, you will perceive the color opposite to the color that you have adapted to. We call this an afterimage color. One of the features of afterimages is that they become stronger, and better visible, when the contours of the adapted color matches the contours of the colorless image presented after the colored image. Therefore, in this illusion you will see the afterimage color of the bull’s eye color that matches the contour of the bubble, which is different depending on the size of the bubble. In other words, your brain uses contours to reinforce color experience.
*** This illusion was a top 10 finalist in the2016 Best Illusion of The Year Awards***
